Redhat – How to determine what version of Red Hat Enterprise Linux the server is running

Try to re-configure em completely

emctl stop dbconsole
emca -repos drop
emca -repos create
emca -deconfig dbcontrol db
emca -config dbcontrol db

The best regards

You can use the lsb_release command on various Linux distributions:

lsb_release -i -r 

This will tell you the Distribution and Version and is a little bit more accurate than accessing files that may or may not have been modified by the admin or a software package. As well as working across multiple distros.

For RHEL, you should use:

cat /etc/redhat-release